Ionizing wire support, especially for electrical precipitators



Nov.l 12, 1940. 2,221,601

IoNIzING wIRE sUPPQRT, ESPECIALLY FoRELEGTRIcAL PREcIPITAToRs- R. A. NIELSEN Filed Jul-y 26, 1939- AI?. Sheets-Shea?I Insulation Fi I.

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Nov. 12, 1940. R. A. NIELsEN IONZING WIRE ISUPPORT, ESPECIALLY FOR ELECTRICAL'PRECIPITATORS 2 Sheets-Sheet 2 Filed-July 26, 1939 @TI L34 INVENTOR ,mas4

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Russell fLNz'elsn ATTORNEY I. Patented Nov. 1.2, i940l l -N is an object of my invention-to avoid the forely in section, of a precipitator cell unit having 5b UNITED STATI-:s PA-TENT orrlca IONIZIN G WIRE SUPPORT, ESPECIALLY FOR ELECTRICAL PRECIPITATORS Russell A. Nielsen, Wilkinsburg, Pai, assignor to WestinghouseLElectric & Manufacturing Company, East Pittsburgh, Pa., a, corporation of Pennsylvania Application Juiy'zs, 1939, serial No. 286,589

11 Claims. (ci. 18s- 7) My invention relates to electrical precipitators thereby raising the cleaning efficiency of the sysemployed to electrically precipitate from air, or tem. other gaseous medium, any contained, or sus- It is a further object'of my invention'to propended, dust particles, or fogs, or other particuvide an intermediate support for ionizing wires 5 6 late matter, and which, for convenience, is herewhich is easy to assemble, and inexpensive to inafter generically referred to as dust. manufacture.

The present invention is an improvement over To accomplish the foregoing object of my inthe gas purifying precipitator comprising the vention, I provide some or all of the wire supports subject matter of Patent No. 2,129,783 issued towith means which do not seriously or apprecilo 10' G. W. Penney, September'13 1938 and assigned ably shield the wire and thereby cut down the to the Westinghouse Electric 8: Manufacturing ionization. In otherwords, the dark regions are Company. In such a. precipitator the gas is first shrunk. I have found that I may emDlOy a DCC- blown through an ionizing zone or chamberand dle through the eye of which the wire can be then through a separate precipitator chamber, strung,` and that such a support or confining 15 115 a signiiicantfeature of the precipitator being means does not seriously affect the ionization of that the ionizing wire is of such small diameter such -supporting or confining points.I that practically utilizable ionization of the sus- Generally, I have found that the supporting" pended particles of dust may be obtained at a means for the wire first, should have no sharp wire-charging voltage producing ionizing curpoints and secondly, should be relatively thin forv zo rents at which negligible ozone generation ocsome extent from the wire.v curs, and the power input is low when the pre- By avoiding the use of points, concentratedv cipitator is used for cleaning air. electrostatic elds are eliminatedand I thereby The ionizing wire of such a precipitator is pref' avoid visible or audible point discharges. While 25 era-bly less than 32 mils in diameter. In the points might yield satisfactory ionization, they 25 usual construction of a precipitator built in acare entirely too erratic in operation, and it has cordance with the aforesaid Penney patent, the been found that such points may become the wire is much finer than this upper limit, andis source of objectionable ozone gerieratibn even' frequently as little as 5 mils in diameter'or even though when originally installed, the apparatusv 3u less. The ionizing wire is usually maintained in appeared to function properly. When using thin,

' some degree of tension, although this is not so rounded supports for the wire as I do, the ionizaessential. o, tion near the supports can be more readily con- In order to minimize breakage and to facilitrolled andis consistent through long periods of tate handling ofthe equipment, the end supports operation. between which the wire is strung must be fairlyl The other desired property of the support, N rigid and strong. If the wire is longer than namely, that it be relatively thin, minimizes the Y about a foot, it is preferable' that it be supported shielding effect of it and I have found that the or conilned'at frequent intervals along its length, thinner the support, the smaller the area of say about every inches, in order to protect it Shielding, the only limitation to the thinness of against vibration and breakage, or in remote the support being the necessary strength to pero cases, against excessive shock. The prior supmit it to perform its function as a -supporting ports introduced dark spots along the wire ex-, or confining means without danger of breaking ,s tending from about one-half to three-quarters or bending., a Y i' of an inch, or somewhat more, on.either side of With the foregoing and other objects in view; the supports, defining regions at whichthe ionizmy invention consists in the features, elements, A

ing current is inadequate so that the dust carand apparatus hereinafter described and claimed, ried by the air or' gas passing through these reand illustrated in the accompanying drawings on gions is not sufficiently electrically charged, thus varying scales, wherein: 1: reducing the efiieiency of the' precipitator. It Figure 11s aview, partly in elevation and'prtgoing defects. separate ionizing and precipitating chambers,

It is a furthervobject o fmy invention to `pro- "and embodying my invention;

vide intermediate supports for anl ionizing wire Fig. 2 is a sectional view of part of the ionizof an electrical precipitator which will have uti ingchamber 'of the cell unit. of Fig. 1, showing lizable ionization in the aforesaid darlg regions, intermediate supporting means for the ionizing 55 wire which, in this case, comprises an assembled U-shaped bracket whose arms terminate in needles;

Fig. 3 is an elevational view of one of the 5 arms of the ionizing wire supporting bracket of Fig. 2 but including a somewhat modified needle; Fig. 4 is a sectional view taken along the line IV-IV of Fig. 2;

Fig. 5 is an elevational view of the eye portion of a self-'threading needle adapted to be used in I place of the ordinary.. needles shown in Figs. 2 A

' current along the ionizing wire for diierent types y of intermediate supports.

A cell unit for an electrical dust precipitator is represented somewhat schematically in Fig-A ure 1, and, except for the features of my invention, may be constructed in accordance with the teachings disclosed and claimed in patent application Serial No. 286,577, of E. H. R. Pegg, filed concurrentlyherewith, and assigned to the Westinghouse Electric & Manufacturing Company.

Such a cell unit comprises an outer casing2 having a dust-ionizing zone or chamber 4 and a dustprecipitator o r dust-collecting zone or chamber 6.

The casing 'itself is preferably rectangular in cross section, and has secured therein for the pre- 40 cipitator zone, collector plates 8 which may be grounded, alternating with insulated collector plates I0. Air to betreated is drawn or forced through the top of the unit past the'ionizing zone 4 where the dust is suitably charged elec'- 45 trically, and is then drawn downwardly through the precipitating zone 6 where the electrically charged dust is attracted to the' collector plates, the air passing outwardly from the bottom of the casing from where it may be led away by any suitable means in any suitable manner.

'I'he ionizing zone usually comprises a plurality of ionizing wires disposed transversely with respect tothe direction of a gas-ow, each ionizing `wire being disposed intermediate two relatively, large grounded electrodes with curved peripheries in cross section so 'as to present curvedv surfaces toward the ionizing wire. In the instant construction and referring to Figs. 1, 2f? and 8, ionizing wires I4 are disposed between a central,

tubular ground electrode I6 and semi-cylindrical `electrodes I8 forming part of the casing 2. The ground electrode I6 extends the length of the casing 2 and has suitable means at each end whereby it may be secured to opposed sides of the 55 casing.

. 'I'he construction of the ionizing unit Ais described in greater detailin the aforesaid application of E. H. R. Pegg and generally comprises a removable unit built about the lectrode I8.

The unit comprises a plurality of bolts 20 extending through the electrode I6 and spaced along its length, the bolts securing one end of insulators 22 to the electrode. To the other' end of the insulators 22 is secured an elongated `bar 7; u in thev fonn of a low channel. Bolt means 2s cooperating with the other ends of the insulators 22 maintain the channel bar 24 parallel to the ground electrode' I6. Thebar 24 isl somewhat 1 shorter than the ground electrode I6 and has its ends symmetrically spaced with ,respect to the ends of the ground electrode.

End brackets 28 are welded or otherwise secured to the ends of the bar 24, and serve as a means for securing an end of the ionizing wire I4 on each side of the electrode I6. The extremities of the arms of the brackets 28 are provided with notches, and the end. of the ionizing wires may be turned once or twice about the extremibrackets 28 as conveniently suitable so that the sharp ends of the Wire will be within the shielded area of the extreme portions of the arms of the brackets. y

The construction thus described resultsin the ionizing wire being suspended, preferably in tension, between the end supporting brackets 28 carried by frame work supported on the ground electrode I6 so that the entire structure comprises a single u nit. However foriextra long units it is usually necessary to support or confine each wire at one or more intermediate points also, and to this end I have devised a novel intermediate support, indicated in its entirety by the reference character 30, which will not adversely affect the efliciency of the precipitator to any objectionable degree. The number of such intermediate supports will, of course, depend upon the length of the ionizer unit, and in Fig. 1, one sup-` port 30 is shown, while in Fig. '7, two such supports are shown. l

Each intermediate support is U shaped in iinal form and comprises a metal bar 32 welded or otherwise secured at its center transversely to the metal bar 24. The bar 32 is provided with two threaded holes 34, the distance between these two apertures being approximately equal to the spacing between the two ionizing wires I4.

Each arm of the support 30 comprises a metal tube 36 having a ne bore therethrough and threaded at one end soV that it may be secured in one of the said holes 34, a lock nut 38 and loci:

washer 40 serving to more securely hold the tube 36 inplace, although it is obvious that the tube 36vmay. be secured to the bar 32 by any other suitable means, either removably or ilxedly. -'Ihe tube 36 is approximately two-thirds the distance between the bar 24 and the center of the ground electrode I6, and each arm is provided with a metal needle 42 occupying the remainder of the distance. The needle has its-point inserted in vthe bore of the tube 36, and the tube vcan then erance :nays/be permitted with respect to the alignment of the eye 44. The needle itself either supports' the wire I4 or contines it so 'that any vibration of the wire will be. damped, and 'It is to be understood that I employed the term "suping of thewire through the eye, but in Figs. 3-

and 5 I show other types of needles which may be satisfactorily employed, and which are of the self-threading type.

The needle of Fig. 3 is similar in all respects to that in Fig. 2, but has been provided with a cut slot 46 so that it is self-threading, the slot being wide enough to permit the ionizing wire to be slipped through it and is preferably disposed at an angle to the horizontal.

Fig. 5 shows the eye portion of a common type of self-threading needle 48 provided with a completely enclosed eye 50 and two separable jaws 52 on eachside of an eye 54. The ends of the jaws 52 are rounded to provide a notch 56 so that the needle may be threaded into the eye 54 by simply slipping the wire into lthe notch and forcing it through the jaws.

The heads of th\needles commonly obtainable are usually rounded and this type of needle is always preferred in constructing the supporting member 30. In fact, even the self-threadingtypes of needle have the extremities of their jaws rounded, and it has been found that this is'almost invariably the case in needles commercially available.

I have found that by employing supporting elements in the form of needles at the intermediate supporting points ofthe ionizing wires, I substantially eliminated to a large extent the shielded ionizing region about the intermediate supporting point.

Fig. 9 is a curve indicating sults I obtained using 13.5 kilovolts between an ionizing wire and the ground electrode, the ionizing wire being 4.5 mils and the ground electrodes having an outside radius of curvature of about and a length of 14", with the axes of two adjacent ground electrodes spaced 3%". The top 'of the needle holder or tube 36 was approximately 1%" from the wire.

The solid'line curve of Fig. 9 represents the ionizing current along the ground electrode on both sides of an arm, such as a tube 36 of about 1%" diameter, or a bar 1/8" by 1%" extending the full distance between the wire and bar 32, the wire being secured to the top of the arm. It may be observed that there is a large region extending somewhat over one-half inchsthrough which there is very little ionization, and that the region through which there is less than normal ionization is spread out. The dot-dash line represents a curve obtained using a self-threading needle of 4 the type shown in Fig. 5 having a diameter of 34 mils while the dash line represents the ionizing current for a similar needle but having a diameter of 24 mils. The value of current represents that flowing to a y' conducting band vinsulated from but rmly wrapped around electrode I6 at dierent distances from the support.

I have found that the smaller the diameter of the needle the greater the ionization current obtained in the region about the supportaand as may be observed from Fig. 9, the use of the 24 mil self-threading needle results in utilizable ionization across the whole region. Additionally, I have found it best to dispose the wire as close to the tip of the needle as possible. These, of

course, are factors in the consideration of the type of needle to be used. -There are, however,

two factors llimiting'the neness of the needles vthe improved re- 3 that may be used, and these are; rst, that the needle may become so line that its tip approaches -a point so that erratic point discharge might occur, and second; too fine a needle may result in too flimsy a support, one which is subject to 6 bending, and perhaps breakage. l,

It is preferable to use a long needle since I have found that if the tube 361s too close to the ionizing wire, the minima shown in Fig. 9 v

tend to fall lower and lower until finally the'10 solid line is approached. A long thin needle supportedv with its eye about 1%" from the tube 36 gave satisfactory results and the size of the needle, that is, its thickness and length, is limited only by the factors of strength required for a practical application of my invention.

Asa result of my invention, the amount of ionization is increased and the extent of the formerly shielded dark regions -decreased about the intermediate supports of the ionizing wires i4. When I refer to shielded or dark regions,

I mean the effect of massive wire-supporting' y arms not provided with the means for reducingA l the shielding effect.

Where sharp points are utilized at the intermediate supports, erratic behavior is usuallyathe result.

.A positive point discharge might occur whichbehaves as follows: As the electrostaticl iield around the point is increased, a short ible in a dark room is first observed accompanied by a hissing sound. This brush discharge causes a generation of ozone, but at slightly highervoltages the brush disappears and only a faint blue dot at the point is visible and the ozone gen'- eration drops oil. No sound is audible; nevertheless it is discharging more current than before. At still higher voltages a larger brush extending toward the other electrode will form and increases'in size and noisiness until an arc ooo ly. Moreover, the field about a point is more highly concentrated than that about a curved surface so that the brush discharge will start at lower voltages than required to cause a similar discharge from the rounded extremities of a needle. unit constructed in accordance with my invention at somewhat higher voltages than would be the case if the intermediate wire supportspontained points in proximity to the ionizing wire.

Another important feature of my invention lies in the practicability of my novel intermediate support. The ionizing wire can be threaded and unthreaded into the eye 54 of the needle without disturbing the rest of the structure. Moreover, Ainasmuch as the arms of the intermediate brackets are removably secured to the bar 32, it. is possible to change the arms in the event they become bent or .otherwise defective.' It is even possible to interchange differentv types of arms with other arms having differentconstruction and functional characteristics.

While I have described my invention in the preferred forms 4of embodiments, and have suggested limits in accordance with my best understanding of the same at the present time, I dez5 brush vis- 30 Accordingly, I may operate an ionizing 55' sire it to bc distinctly understood that I am not altogether limited to these limits or understandings, or to the forms of embodiments shown in the drawings since the equivalent of a needle can be readily manufactured, the needle being preferred at present because of the ease with which it can be procured and because of its relatively small cost.

. I claim as my invention:

1. A device of the class described generally having an ionizing chamber an`d a precipitating chamber successively in the path of a gas-flow; said ionizing chamber having ionizing means disposed transverse to the gas-ow, said ionizing means comprising ground electrode means, an

ionizing wire, and supporting means to support said wire insulated from and in spaced relation to said ground electrode means, said supporting means comprising ajsupporting element contacting said Wire and having rounded exterior surfaces thereby to avoid point discharges.

An item for an electrical precipitator which removes' dust from gases by providing an ionizing zone through which the gas flows so that the dust therein may be ionized, comprising an elongated, relatively large electrode, a plurality of insulators, means to secure one end of said insulators and said electrode together with the insulators spaced along said electrode, armed"v brackets supported by the other end of said insulators, a relatively ne'ionizing wire, the arms of said brackets foiming supports for supporting said Wire in spaced and insulated relation to said electrode, one of said arms comprising a needle having its point away from said Wire, and anl eye through vwhich said Wire passes.

3. A device of the class described generally having an ionizing zone and a precipitating zone successively in the path of a gas-flow; sai'd ionizing changer having ionizing means disposed transverse to the gas-110W, saidionizing means comprising ground electrode means, an ionizing Wire, and supporting means to support said wire insulated from and in spaced relation to said ground electrode means, said supporting means comprising a member having a needle protruding therefrom with its eye\aWay from said member, said Wire passing throu'gh said eye.

4, An item for an electrical precipitator which removes dust from gases by providing an ionizing zone through which the gas ilows so that the dust therein may be ionized, comprising, an elongated substantially-straight tubular electrode, a pluralityof insulators, means to support an end of each o f said insulators on said electrode intermediate the ends thereof, a bar secured across the other ends of said insulators and extending substantially parallel to said electrode but of lesser length with the ends of the bar within the ends of the electrode, a plurality of spaced U-shaped brackets secured to said bar with their arms straddling said electrode, and in spaced relation thereto, said brackets comprising a second bar transverse to said rst bar, -said 'arms being removably secured to and extending from the said second bar, each said arm including an end portion comprised of a needle with its eye away from said bar.

5. In an electrical precipitator which removes dust from gases by providing an ionizing zone through which the gases pass so that the dust therein may be ionized, the combination With a relatively'fine ionizing wire, said gases passing near said Wire whereby the dust in the said gases is charged, and means for supporting said wire 'at' each of its ends, of means for coniining said end with rounded edges, said free end being provided with an opening through which said wire passes.

6. In an electrical precipitator which removes du-st from gases by providing an ionizing zone through which the gases pass so that, the dust therein maybe ionized, the combination with a relatively fine ionizing wire for ionizing said zone for charging the dust in the said gases, of means for supporting said wire in said zone, comprising a thin metallic rod having a free end with rounded edges to reduce possible. discharges from said edges, said free end being provided with an opening throughwhich said wire passes, said rod being of a relatively small size whereby the shielding eiect of said rod on the ionizing current, from said Wire near said rod is limited.

'7. In an electrical precipitator which removes dust from gases by providing an ionizing zone throughl which the/gases pass so that the dust therein may be ionized, the combination with a secured to each end of said bar, and a needle for f each arm, each of said needles being secured to its corresponding arm with its eye outward, the said wires passing through said eyes.

8. In an electrical precipitator which removes dustl from gases by providing an ionizingzone through which thegases pass so that the dust therein may be ionized, the combination with a relatively fine ionizing Wire, and insulating means, of means to connedly support said wires from said insulating means, the said supporting means comprising an elongated bar, an arm removably secured to each end of said bar, and a needle for each arm, each-of said arms having a small bore thereininto which the pointed end of the corlresponding needles extend, the arm` and'its cor- .relatively small supporting element contacting said Wire and having rounded exterior surfaces thereby to avoid point discharges.

10. An electrical precipitator for cleaning dust from a flowing gas, said precipitator comprising,

an ionizing Wire, means forl supporting said Wire comprising end supports and intermediate confining means, said gas flowing near said Wire and confining means whereby the dust in the gas may be charged, said conning means comprising a relatively thin metallic rod having a free end with rounded edges, said free end being provided with an eye, said rod being transverse to said Wire,

said wire passing through said eye,'and said eye means in the path of the gas-flow, said conning being of the self-threading type. means comprising a thin rod having a free end 11. An electrical precipitator for cleaning dust provided with a small opening through which from` a flowing gasl said precipitator comprisingV .saidrwire passes, whereby vibration of said wire 5 an ionizing wire having a diameter of less than is reduced, said rod being of a relatively small 5 32 mils, and of such neness that substantially: cross-sectional area whereby any shielding eiect l utilizable ionization is obtained with negligible on the ionizing current from said wire near said ozone generation, and supporting means for sup-f rod is limited. porting said wire, said supporting means compris- 10 ing end supports and intermediatel confining RUSSELL A. NIELSEN. 10 

